1. Field of the Invention
The present invention relates to a server system for performing communication over a wireless network, and more particularly to a server system for performing communication over a wireless network that comprises a server device with a buffer manager capable of automatically pausing an encoding operation when data is stored outside a predetermined memory area to avoid transmission delay at the server device transmitting predetermined data to a client device and an overflow of data due to the transmission delay.
2. Description of the Related Art
Conventionally, a server system for performing communication over a wireless network includes one or more client devices 20 and a server device 10 for carrying out wireless communication with each client device 20 and carrying out a control operation. A wireless network modem is mounted in the server device 10 and the client device 20.
FIG. 1 is a block diagram illustrating a conventional server system for performing communication over a wireless network. Conventional drawbacks will be described with reference to FIG. 1.
The server device 10 coupled to an external medium such as a radio, a television (TV) antenna or etc. can receive moving picture data. Moreover, the server device 10 coupled to a cable network or an Internet network can receive digital contents transmitted from a specific server.
In case where video or speech signals are converted into digital data and the digital data is stored without being compressed, the uncompressed digital data occupies a large storage space of a memory provided in the server device 10 and the wireless network is unstable. Consequently, transmission load on the wireless network increases.
If the client device 20 makes a request for predetermined data transmission, the server device 10 and the client device 20 initiate wireless communication. A distance between the portable client device 20 and the server device 10 can vary when the portable client device 20 such as the web pad is moved during the wireless communication. Alternatively, frequency interference and radiowave impairment can be caused by a predetermined mobile terminal (e.g., a mobile phone, a wireless phone, a radio or etc.) that performs radiowave communication. In this case, transmission bandwidth of the wireless network is reduced and hence data transmission delay occurs. That is, the wireless network can easily be unstable because the number of communication interference parameters is large in the wireless network as compared with a wired network.
As described above, when the data transmission, delay occurs, a buffer provided in the server device 10 overflows, the buffer overflow can bring server system shutdown, and data cannot be identified in real time because of playback delay at the client device 20. For this reason, the stability of a total client-server system performing wireless communication can be degraded.
This problem can be maximized when the data transmitted from the server device 10 is streaming data such as real-time audio on demand (AOD) or video on demand (VOD).
FIG. 2 shows layer architecture for a server device and a client device. An application program is started in an application layer for controlling each device. Media access control (MAC) layers allow a plurality of client devices to share the server device, and are lower layers between the server device 10 and the client device 20.
That is, an encoder 11 encodes data to be transmitted to the client device 20 in response to a control signal issued from the application layer. The encoded data is transmitted to the client device 20 through a network renderer 12, i.e., a wireless network modem in a wireless fashion.
If data congestion is caused by wireless network variation, a bottleneck occurs in the MAC layer, the network renderer 12 and the encoder 11 in this order. As the bottleneck is continued, data in a buffer of the encoder 11 is congested and a system is stopped, such that the system can be unstable.